


The Sweetest Lie

by Raikishi



Series: The Lie in You [1]
Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Ambiguous Relationships, Angst and Feels, Heavy Angst, M/M, One-Sided Attraction, Pining, Soulmates, Unhappy Ending
Language: English
Status: Completed
Published: 2020-07-26
Updated: 2020-07-26
Packaged: 2021-03-05 22:01:59
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,622
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25532548
Author URL: https://archiveofourown.org/users/Raikishi/pseuds/Raikishi
Summary: Blaiddyds did not have soulmates.“It is for the best that the ruling houses are unbound,” Lambert had said with a little sparkle in his eyes, “Court politics are troublesome enough. Imagine your soulmate represented another country. Trade would be difficult to negotiate when you are unable to manage even the smallest lie to their face.”“I would simply not lie,” Dimitri had huffed, folding his arms, "Ever."Soulmate AU in which you cannot lie to your soulmate
Relationships: Dimitri Alexandre Blaiddyd/My Unit | Byleth, implied Edelgard von Hresvelg/My Unit | Byleth
Series: The Lie in You [1]
Series URL: https://archiveofourown.org/series/1999264
Comments: 13
Kudos: 88





	The Sweetest Lie

Blaiddyds did not have soulmates. None of the descendants of the Ten Elites did. As if the Goddess had decided they all had enough gifts from her and needed to learn temperance. 

As a child, Dimitri had stomped his foot in protest. What a thing to hold back from him. He deserved another soul meant for him as much as anyone else did. He was the prince! He was very good with his lance. And he was very patient. Even when Felix cried at their games. Or when Ingrid picked a fight because she wanted to be knight instead of princess. Or when Sylvain chased after the maids instead of paying attention to their game. 

His father had laughed uproariously at the declaration and ruffled his hair.

“It is for the best that the ruling houses are unbound,” Lambert had said with a little sparkle in his eyes, “Court politics are troublesome enough. Imagine your soulmate represented another country. Trade would be difficult to negotiate when you are unable to manage even the smallest lie to their face.”

“I would simply not lie,” Dimitri had huffed and folded his arms, "Ever." 

“Ah, yes. Such wisdom from my little lion, we could all learn a thing or two from you,” Lambert had nodded sagely, “Then perhaps you can tell me who broke the arms from the statue in the front gardens?”

“I - um … well …”

* * *

In hindsight, Dimitri thinks it is probably for the best that there is no one for the Blaiddyds. No one to chase after Rufus as he in turn chases after other women. No one for him to decree bluntly to their face that he was more interested in variety than the same old hat day in and out. Dimitri had certainly not wanted that invidious truth shoved in his face.

The acknowledgment follows Dimitri to Duscar and out. Solidifies in his chest as he turns to courtiers and advisors in the Blaiddyd halls and convinces them he’s fine in the days following. That yes, his father’s death was a terrible thing. That the Tragedy of Duscar was a cruel injustice but one he had survived.

He was relieved there was no one to confess to, about the darker him that had slithered out from beneath the corpses and made a home in his heart. No one to burden with his sins. To see into the depths of his soul and drown with him in the darkest part of himself.

No one ... 

Until the Professor.

“Are you alright?” 

Dimitri startles, his elbow knocking the candlelight and the Professor steps nimbly out of the way, graceful on his feet and quick as he had been on Gronder Field. Byleth tramples the flame beneath his boot decisively, extinguishing the little light before it can latch on the floor and grow as an inferno.

“My apologies!” Dimitri says, bowing low, “I’m afraid I was lost in thought - no, that is no excuse for such clumsiness. Are you injured?”

Byleth slowly shakes his head, a little furrow on his brow as he examines his sleeves.

“It’s quite late Professor,” Dimitri says, shoving aside the ledgers he had been pouring over, “You should be in bed.”

“As should you,” Byleth says, tilting his chin at the books, “It’s a little late to be studying. Has Hanneman assigned so much work you have to look over these at this time of night?”

_“Yes,”_ burns the back of Dimitri’s throat and dies before it reaches his lips, set to flame and falling into ash. 

“No. I have trouble sleeping,” Dimitri blinks at the words, confused.

It was a fact he disliked sharing.

“Oh,” Byleth says and the look in his eyes is too knowing. Too full of understanding in a way Dimitri cannot bear, “Did you have to deal with bandits as a first mission as well?”

“Some thieves in the Kingdom,” Dimitri says, testing the words on his tongue and they come easily enough. He shakes off the slip as weariness, rubbing his eyes.

“It’s never easy taking a life,” Byleth says. 

“No,” and then, _“But it is a bitter truth I am accustomed to it.”_

Vanishes like smoke in the air between them. 

Realization sits cold in Dimitri’s stomach. A stone rock, jagged and cruel, weighing down in the pit of him and piercing him through with understanding.

Byleth shakes his head, lashes dimming. The few candlelights make the shadows longer. Fan them over the clean cut of his cheek.

_My soulmate is lovely,_ Dimitri thinks hysterically, his heart pounding so loud it is a wonder the Professor cannot hear. 

“I know I’m not your Professor, but if you would like some company –“

_“No,”_ goes the same way as Dimitri’s previous answer. 

It burns into ash on his tongue and vanishes with a bitter aftertaste. Another reply pries at his mouth, struggling to shape his lips and break the air between them.

_“Always. I hate being alone.”_

And.

_“Please, as my mate, then surely –“_

Dimitri clamps down on his tongue to hold the reply back, feels the words tug and pull at him, urgent and pressing as they hover on his lips. Wanting to be spoken. He jerks back so suddenly the chair behind him shrieks, “I … I think I shall retire to my room. Apologies, Professor.”

Byleth’s expression wavers a little, the furrow between his brows deepening into something like concern. He raises his hand to graze Dimitri’s shoulder but does not touch. Dimitri does not allow him as he turns tail and flees. 

For one long hysterical moment, in the space between the library and stairs, Dimitri thinks Byleth might follow. Might come and chase after him. Corner him in the walls and lay a hand on his shoulders. That his soulmate might find him in the dark and stretch his hand out, asking him to take it. 

He strangles the part of himself that craves the touch. 

* * *

Dimitri had asked Ingrid once, what it felt like to try and lie to Glenn.

She’d scrunched up her nose as she sought the words. Trying to put to form something intangible with a child’s vocabulary. 

“I can’t,” she’d decided on and they had all pressed her on that response. Three stubborn boys unable to accept an answer so vague until she’d waved her lance and sent them scattering.

Dimitri understands now what she had meant.

The words simply do not come. They fall off his tongue, collapsing into oblivion and the truth would rise, bright and bloated and unstoppable unless he put a hand to his mouth or bit his tongue, physically holding them back. Thankfully, he does not have many opportunities to try for deceit with Byleth. The Professor is too busy with the Black Eagles among the many other duties Byleth has picked up.  


Dimitri watches the Professor run about the monastery and it is like watching a storm in human form. Byleth holds lessons on the training grounds and then runs to promised mealtimes with students. On free weekends he fishes in between tea parties in addition to performing weapon maintenance, overseeing battalion training, and personally returning various lost items to all.

The times Dimitri and the Professor share space are few and far in between. Dimitri tells himself it’s better that way. There are fewer opportunities for Byleth to twist ugly truths from Dimitri's tongue with his simple presence alone.

It also means Dimitri is unprepared for the times he does.

_“No, please, I do not care much for sweets,”_ Dimitri tries to say when Byleth offers him the last sweet bun in the dining hall.

“Yes, please, if you would allow me,” is what comes out. He ducks his head, cheeks aflame as the rest of the truth follows, “These were my favorite as a child.”

“Hm,” Byleth says and then inexplicably, “It suits you.”

“W - I – _“_

“ _m afraid I don’t know what that means!”_

He can’t manage the lie. The implications have wrapped themselves around his head, drawn a color to his cheek, and set his heart pounding.

“My my, having fun?” Edelgard raises an eyebrow at Dimitri as she stares him down, coolly assessing as she tracks the blush on his cheeks before turning back to the Professor, “Shall we?”

“Would you like to join us, Dimitri?” Byleth asks. 

“Yes,” he blurts out before he can think and the blush digs deeper when Edelgard turns a critical eye on him. 

Excuses come and go, flitting through his head in a mad scramble. Falling to pieces each time he looks at Byleth. 

It is a long moment before he can summon a more innocent truth to offer, “It’s been a long time since we’ve shared a meal, Edelgard.”

Her brows furrow but her shoulders loosen some of their tension as she says, “I suppose as future rulers of our respective kingdoms, we should at least be amicable.”

A part of him, that same child who’d duck his head when she scolded him for missteps during a waltz, ducks now in embarrassment. How like him to be caught by longing of the past while she looks steadily forward to the future. 

That alone had not changed despite their years apart.

Byleth’s touch on his arm is feather-light, drawing him back and guiding him to their table. The Black Eagles greet him cheerfully enough as he takes his seat on Edelgard's right and Byleth to her left. A guest of honor and his spouse. The thought burns through him but he forces it quiet. 

For the first time in a long while, he feels warmed to the bone as he joins sister and soulmate at their table. 

And if he dreams of them all that night – 

Byleth by his side as his consort. Edelgard at the guest seat in the Fhirdiad court. Their smiles welcoming him to the meal. 

– Well, he has no one to confess to but Byleth who does not ask.

* * *

He stops trying to lie on the rare occasions he finds Byleth in the halls, instead reveling in the Professor’s steady warmth and the easy truth that leaves Dimitri’s mouth.

“Yes, I would like your company,” whenever Byleth finds him in the library in the dead of night. 

“Yes, please I would like another spar,” on the training grounds on Byleth’s free weekends.

“No, I suppose it does bother me,” when Byleth asks him if he minds that Felix has joined the Black Eagles, “But I suppose I cannot fault him. This was … expected.”

Byleth tilts his head, a question on his face and Dimitri is inordinately thankful it goes unspoken.

_“He hates me for his brother’s death and rightly so,”_ is a cruel truth he does not wish to burden Byleth with.

Not tonight. Not in the few moments the ghosts go quiet and leave him some reprieve. Not when it has been so many moons since Byleth has found him in the knight’s hall and deigned to join him for a long night. 

Dimitri takes a sip of tea he cannot taste, fondly amused when he watches Byleth take a sip of his own whiskey and tea blend. Ever the mercenary even below a knight’s banner. Blaiddyd’s lion flag hangs low over the Professor’s head as he curls into the lounge, his bare feet tucked beneath him as he blows lightly over his own cup. 

The moment so intimate the ghosts do not dare intrude and in the silence, Dimitri thinks he would like to touch a hand to the Professor’s cheek. To see him like this in Fhirdiad Castle. He wants to be greeted by Byleth on a blue chaise lounge. Without armor and metal between them. To lean down and feel the curve of the fine bone and the sweet curve of Byleth’s jawline. To have Byleth touch him as well, and to – 

“Something on your mind?”

Dimitri drowns his reply with a burning sip of tea that makes him choke, doubling over as he does. 

Byleth’s hand touches his back, patting gently and Dimitri seizes in alarm, a fire roaring through him as he finds himself staring into Byleth’s eyes. The Professor is so close. His expression full of concern. 

Eyes only for – 

Dimitri presses up before he can stop himself. Angles a kiss over the sweet curve of Byleth’s mouth as he’d seen Sylvain do to his many bed partners, tracing the light seam of Byleth’s mouth eagerly as he –

“No,” Byleth holds him down, fingers digging hard into Dimitri’s shoulder, a look of surprise in his eyes as the barest hint of a blush sweeps his cheeks. His bottom lip is shiny and Dimitri longs to trace after it again, “I don’t want –“

_“You.”_

Dimitri completes the sentence for him as the Professor flees.

The words twist in his skull, digging into his head like a crown of thorns. 

His soulmate did not want him. 

Or … he lied. 

And that would mean –

A broken grimace of a smile twists Dimitri’s mouth, sharp and bitter as if he were trying to swallow a handful of nails rusted through. The iron flakes of them filling his mouth as he sits back on his heels, head spinning with new knowledge.

* * *

Dimitri pays attention more after. Needing to know. To understand if the Goddess, cruel as she was, would play this joke on him as well. That it was not enough for her to take his father, his stepmother, and his closest knights in fire and blood; but, that she would deny him his soulmate also. 

“Are you alright?" Dimitri asks after Remire because he sees the tremble in Byleth’s hand as he carries a little girl to the medical bay. 

The Professor is stripped down to his undercoat. His top jacket and cloak had been repurposed to wrap the corpses. His arms are a mess with burns and new wounds. His face and chest are painted with another’s blood. There’s a familiar exhaustion in his eyes. The same anguished weariness that followed Dimitri out of Duscar, ghosts latching to their ankles screaming their agony. 

Byleth is, by all definition, not alright. 

But it does not stop him from turning to Dimitri, a little quiver in his mouth, and replying, “It’s nothing.”

* * *

“Sometimes, you are impossible to read,” Dimitri tells him at the Goddess Tower, quashing the little fever bright flick of hope in his chest when Byleth joins him, “When we first met, I thought of you as someone who felt no strong feelings about killing your enemies. Someone who did not care about anyone. I see that is not true.”

Byleth tilts his head in a question, the gesture so adorable Dimitri cannot help the stir of affection in his chest.

“You care about the Black Eagles. I saw it when you came to Edelgard’s aid on Gronder,” he says, holding back the part of him that was still that young prince. Stamping his feet and demanding his mate. Shouting that he not be so denied. He ruthlessly extinguishes his bitter jealousy, “Their kind and beloved Professor.”

“I care about you too,” Byleth says but he comes no closer, hovering awkwardly by the open windows.

A lie. 

Dimitri wishes he did not have to be so cruel. 

Byleth’s gaze, when it meets Dimitri’s is tentative and uncertain, no doubt thinking of Dimitri’s lapse in judgment so many months ago. Slowly, he comes closer and Dimitri wants it again, entire body aching with desire. Wants to reach out – 

Dimitri doesn’t have to strangle the desire burning in his blood because Edelgard does it for him.

“Dimitri,” she greets as she crests the landing, “It’s a surprise to see you here.”

Not a surprise to see the Professor then. 

Dimitri offers them both a smile and a bow, understanding where his place was not. Dismissing himself. When he glances back, the Professor has his head bowed towards Edelgard. The two of them speaking in quiet voices and Dimitri understands now that the table he’d dreamt of was in Enbarr and not Fhirdiad.

* * *

“I want to be alone,” Byleth tells Edelgard when Jeralt passes, a stony solemnness in his voice that succeeds in pushing her out the door of his room.

He says nothing when Dimitri enters.

Byleth looks so small in his bed, eyes red as he stares stoically at the ceiling, his jaw clenched. Tired of crying but unable to relinquish the grief. Dimitri remembers those days. Remembers the blood spotting the back of his throat as he’d screamed his grief at undeserving servants and thrown them aside. Wanting space to wallow in his own misery. Needing somewhere he could curl up around himself and hold himself in place of a lost father.

Byleth no doubt wanted the same. 

Still, Dimitri cannot stop himself from walking across the room and making a space for himself at the foot of Byleth’s bed.

“Do you want me to leave?” Dimitri asks.

“No,” Byleth says and then grimaces. 

The displeasure in his face betrays the lie.

Something dark blots Dimitri’s heart at the difference in the response he has garnered in comparison to Edelgard's. Something hideous and full of despair whispering that perhaps it was Edelgard Byleth could not lie to. Asking why von Hresvelg deserved a mate when Blaiddyd – 

“Then I shall stay,” Dimitri says and Byleth does not respond, only curling up in a little ball that makes him look smaller, “It is the least I can do.”

As his student. As his mate. As his – 

Nothing, Dimitri reminds himself of the thought, drills it into his own foolishly thick skull. His mate did not want him and he was a stupid man doomed to worship at the feet of another who would kick him away.

But he cannot make himself go. Cannot look at the tremble in Byleth’s shoulders and listen to the barely controlled hitch in his breathing and turn his back. 

The Goddess was cruel indeed. To offer a mate for Blaiddyd that would not be his. To make him love his mate so dearly it broke him through but then severe their connection there. Making a mockery of her own laws to torment him further.

Look here, Blaiddyd, at the mate you insisted upon. But only look and never touch for you will never have him.

* * *

The Goddess is not done with him then.

She wears the lesson into his soul in the months that follow. Dig in beneath skin and bone, into the very core of him as the mask falls from the Flame Emperor. 

“Kill her,” Rhea commands.

And Byleth –

Byleth chooses Edelgard.

Dimitri does not follow the fight that breaks out. Barely remembers the skulls that break beneath his monstrous hands. Half deaf to their final cries. He only sees the mate that is not his, catches him as the Eagles begin their retreat.

“You said you cared about me,” Dimitri says the words numbly around a mouthful of sand. 

His head hurts. Has been aching since the moment Edelgard was unmasked. The ghoulish faces of those once loved stretched into macabre distortions of what they had once been. He is vaguely aware that he is holding the Professor’s hand too tightly. That any more he might shatter armor and pierce bone, break it like the delicate wing of a bird. 

He might do just that.

If it would keep Byleth from flight – 

He makes himself let go, shaken by the thought. Acid rising to his throat and making him choke as revulsion washes over him.

Byleth opens his mouth, words lost beneath Rhea’s scream as she shatters the ceilings. At their back, Annette and Sylvain throw spells at the crowd of Imperial soldiers. Dedue grunts as he shields Ashe and Mercedes from a volley of black magic, buckling beneath their spells. 

Ingrid calls for Dimitri as king and leader but he remains rooted in place, bound by his heart.

“I want you with me,” Dimitri breathes out the final truth in desperation, “Even if you are not mine. Even if your heart follows another. I want you by my side in Fhirdiad. As my ally, my beloved … my beloved –”

“Dimitri,” Byleth breaths, a tremble in his voice as he holds himself carefully away. The stoicism has been wiped clear of his face, something broken and haunted taking its place as he edges away.

What monster must he find on Dimitri’s face to shake him so? 

“Professor!” Edelgard shouts.

And the little good-will Dimitri had had for his step-sister vanishes. Their shared years in Fhirdiad evaporating like smoke. He grabs for Byleth, holding fast, intent on –

Byleth’s expression shatters as he reaches for the Sword of the Creator, cutting himself free with firm decisiveness. He does not look back once before vanishing in smoke and chaos.

Etching the truth into Dimitri’s armor. 

A cross over his heart, burning the reminder into his soul. 

Blaiddyds did not have soulmates. 

“They have no need for them,” Lambert snarls at him, skeletal hands caressing his cheek, his lip peeling from a broken jaw as he spits at him, “Or did you think you, alone, deserved such happiness.”

_No. Never father._

His retort falls silent beneath the wail of ghosts. More voices lift to join his father’s in berating Dimitri for the fool he was. Screaming for their vengeance. Demanding payment in blood and nothing else. The echoes of their final words before death beating against Dimitri’s skull. 

Familiar hands grab for Dimitri’s face and arms. His jaw. His throat. 

Glenn. Stepmother. Father.

No longer people but chains nows, tearing into his skin and flaying him through. 

_“I care about you,”_ the sweetest lie follows him into the dark, echoing beneath the howl of the dead as the ghosts take him. 

**Author's Note:**

> Me: god i love fluff.  
> Also me: crimson flower dimileth :v  
> \---  
> I might write Byleth's viewpoint next
> 
> Open to interpretation relationship but from my POV, Dima's just being dumb and misreading the whole situation
> 
> Edit: I did NOT write Byleth's viewpoint but I wrote an AU fix-it lol (can't take my own angst sometimes ; o ; )


End file.
